Kokushibo is reserved, silent, and aloof. He rarely speaks; when he does, he talks in a slow and emphatic manner that gives more gravitas and authority to his words. 
Kokushibo demonstrates unwavering loyalty towards Muzan Kibutsuji, as he carries out his actions solely to fulfill Muzan's objectives. When reprimanding individuals, his words can be harsh, bordering on cruelty. He is Upper Rank 1 in the Kizuki, and his most defining feature is his six eyes.